1. Field of the Invention
The present invention pertains to a catheter, and more particularly, pertains to a flexible microcatheter having continuous variability of stiffness or flexibility along and about the length of the flexible catheter. Embedded flexible braid wires surrounded by layers of varied hardness flexible plastic allows flexibility in different degrees for tracking and navigating along a tortuous vascular or other path.
2. Description of the Prior Art
Prior art catheter devices for use in small and tortuous vascular paths required catheters of minimum profile while yet requiring a great degree of flexibility. A catheter of minimum profile often could be flexible to a fault in that the catheter would tend to kink in a tight radius path, thereby causing a lumen flow restriction or stoppage. Difficulty could also be encountered in advancing the catheter along a path or application of torque-transfer, as the minimum profile structure did not provide the structural integrity required for advancement or twisting without the tube bending or kinking at various points along the catheter length.
The present invention provides a flexible microcatheter which overcomes the problems of prior art devices.
The present invention, a flexible microcatheter, is fashioned, in part, by a one-piece composite catheter tube composed of several layers of plastic including a polyethylene or polyamide copolymer or fluoroplastic inner layer or polyether block amide, a stainless steel or other braid material aligned over and about the inner layer to provide kink resistance and to increase torque transfer, and an outer layer of two polyamide and polyether or polyurethane based materials along and about the braid material and the inner layer. The inner layer has a constant hardness or flexibility while the length of the outer layer is comprised of regions of continually varying or different hardness or flexibility as determined by the composition of resin used to fashion the regions of the outer layer. The regions included are the distal region, a mid region of continually varying hardness located proximally and adjacent to the distal region and a proximal region located adjacent to and proximal to the mid region. The distal region exhibits the greatest amount of flexibility followed by regions of increasingly lesser flexibility in each successively and proximally located region of flexibility.
According to one embodiment of the present invention there is provided a flexible microcatheter having a Luer adapter, a strain relief and a one-piece composite catheter tube extending therefrom. The one-piece tube is comprised of a flexible plastic inner layer of constant hardness, a braid aligned over and about and along the inner layer and a flexible plastic outer layer having regions of different or continually varying hardness aligned over, about and along the braid and the inner layer. Marker bands and a distally located tip are included distally on the one-piece composite catheter tube.
One significant aspect and feature of the present invention is a flexible microcatheter having a variable degree of flexibility along its length. There is a mid region of flexibility which is continually varying.
Another significant aspect and feature of the present invention is a flexible microcatheter having a one-piece composite catheter tube.
Yet another significant aspect and feature of the present invention is a flexible microcatheter which encapsulates a braid between an inner and outer plastic layer, and is resistant to kinking and ovalization with bending.
Still another significant aspect and feature of the present invention is a flexible microcatheter which allows torque transfer.
A further significant aspect and feature of the present invention is a flexible microcatheter having a relatively stiff proximal region for application of push force to the distal flexible region(s).
A still further significant aspect and feature of the present invention is being able to vary stiffness without varying the outer dimension.
Having thus described one embodiment of the present invention, it is the principal object hereof to provide a flexible microcatheter.